Push-off and propulsion of the body in normal and abnormal gait. Correction by ankle-foot orthoses.

The biomechanics of push-off and propulsion are described as part of normal gait. Deviations from a normal gait pattern, as well as secondary complications, are discussed in reference to common limps, such as gastrocnemius and soleus weakness and the hemiparetic stroke gait. In addition to the lack of propulsion, major abnormalities include the instability of the knee and the lack of motion at the ankle, associated with muscle imbalance and spasticity. The correction of the abnormalities by ankle-foot orthoses is described in quantitative terms. Proper adjustment of the orthosis is essential for optimal guided correction.